caster (US) noun
or British castor /ˈkæstɚ/ Brit /ˈkɑːstə/ plural casters
or British castor /ˈkæstɚ/ Brit /ˈkɑːstə/ plural casters
Learner's definition of CASTER
[count]
: a small wheel attached to the bottom of something (such as a piece of furniture) to make it easier to move（家具等底部的）小脚轮，万向轮